Method of and furnace for annealing



April 29 1924.

C. R. STEVENS METHOD OF AND FURNACE FOR ANNEALING Filed Dec. 17. 1921 INVENTOR Char/$95 R 6/91/6105 ATTORNEY \MTNESSES:

CHARLES R. STEVENS, OF WILKINSBULRG, PENNSYLVANIA, ASSIGNOR '10 WESTING- fAT HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

METHOD OF AND FURNACE FOR ANNEALING.

Application filed December 17, 1921. Serial No. 523,079.

To all whom it may concern.-

Be it known that I, Crmnnns R. STEVENS, a citizen of the United States, and a resident of lVilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Methods of and Furnaces for Annealing, of

which the following is a specification.

This invention relates to furnaces for and methods of annealing metals and more particularly to furnaces and methods especially adapted for the annealing of non-ferrous metals, such as copper and copper alloys.

Hitherto, in furnaces for annealing metals 5 such as copper and copper alloys, the structure thereof was such that the metal to be annealed passed through a body of water on entering and leaving the furnace. One type of furnace embodying this principle consisted of a heated chamber from which air was excluded by means of super-heated steam therein, and an endless belt, passing under water seals, was caused to slowly progress through the heated chamber. The

metal to be annealed was placed on the endless belt, passed under the water seal at one end of the furnace, then into the heated chamber, where it was annealed, and then passed out through the water seal at the opposite end of the furnace. Another furnace embodying this principle included a vertical heated chamber, the lower end of which was sealed by water and into which amovable table, carrying the metal to be annealed, was inserted from below by suitable mechanism.

It will be noted that both types of furnaces embodied a water seal to prevent access of air to the material being annealed.

This was necessary in order to prevent oxidation of the surface of the metal and to prevent tarnishing thereof. However, I have found that the water seal through which the annealed metal must pass causes 5 water tpenetrate into the, mass of metal,

which is generally in the form of a roll of wire. It is practically impossible to remove all the water from the metal and in a short time the contained water causes a reaction wit the metal, thus oxidizing and chamber into which the material to be annealed is placed and is heated to the proper annealing temperature. A gas, which has been purified in a special manner, is caused to pass over the material in the retort during the annealing operation to prevent oxidation or tarnishing of the surface of the metal. In such furnace, no oxidation of the material can occur and no water, either in the form of superheated steam or in the liquid form, is allowed to come into contact with the metal. As a result, the metal is not only bright when removed from the furnace but may be stored for an indefinite length of time without becoming oxidized and tarnished.

In the accompanying drawings constituting a part hereof and in which like reference characters designate like parts,

The single figure is a perspective view of my new furnace arrangement for annealing metals, such as copper and copper alloys.

I provide a furnace chamber or retort 1, preferably of the horizontal type, closed at both ends by any suitable means, such as plates and bolts, a shown. The retort is mounted in a furnace 2 having openings 3 in the lower end thereof for the insertion of suitable burners, not shown, for heating the furnace chamber or retort and provided with a stack .4 for the removal of gases of combustion. There is further provided a purifying chamber or retort 5 set in a furnace 6 which is heated usually by the gas used in providing a. neutral atmosphere in the furnace chamber or retort 1.

Gas from any suitable source, such as natural gas or artificial illuminating gas, is caused to pass into pipe 7, one of the branches 8 of which, provided with a valve 9, communicates with one end of purifying chamber 5 which may be filled with suitable material for purifying the combustible gas. The material may be carbon in any form, such as charcoal or coke, or may consist of a suitable metal, such as copper or iron turnings capable of removing impurities from the gas. I generally prefer to use charcoal at the entrance end of the purifying chamber 5 and some-copper turnings at the exit end of said chamber.

Exit pipe 10 from the opposite end of chamber 5 communicates with pipe 11 which is provided with a valve 12 and is connected to one end of the furnace chamber or retort 1. Pipe 13, at the opposite end of retort 1, provides a means for removing the gas entering the retort through pipe 11. Branches 14 and 16 from pipe 13 are provided with suitable valves 15 and 17, respectively, the pipe 14 communicating with the atmosphere and the pipe 16 with a pipe 18, one branch 19 of which is connected to burners (not shown) for heating the purifying chamber 5 and the other branch 20 of which is provided with a valve 21 and is connected to the main gas pipe 7 and its branch pipe 8.

Pyrometer tubes 22 and 23, placed in chambers 5 and 1, respectively, are connected to suitable pyrometers 2t and 25, respectively, for reading and recording the temperatures in said chambers.

In annealing metals, the material in the form of wire or bars is placed in retort 1 and the ends of the retort sealed. Gas, generally natural gas, is caused to pass through pipes 7 and 8 into chamber 5, through pipes 10 and 11 into the retort 1 and through pipes 13, 16, 18 and 19 to the burners which heat the chamber 5. Generally the temperature of chamber 5 is maintained between 600 and 700 (1, causing reactions to occur therein, whereby hydrogen and oxygen in the free state are removed from the gas, and sulphur is either combined with other constituents of the gas or with the materials used for purification. The heated purified gas passes through the retort 1 which is heated to any suitable temperature, generally 200 to 350 C. for various grades of copper wire. The annealing is conducted at the desired temperature for several hours, after which the furnace is allowed to cool to about 70 C. when the contents of the retort 1 are removed.

My invention, as will be readily seen, provides a cheap furnace construction which is effective in annealing non-ferrous metals with the expenditure of a minimum amount of fuel for heating the same, since the gas is utilized in one stage of the process for preventing oxidizing and tarnishing of the metal is utilized at a later stage for heating the purifying chamber.

Although I have described my invention as embodying the utilization of gas from the retort 1 for heating chamber 5, it is obvious that the said gas may be utilized for heating the retort 1 or may be conducted away and utilized for a different purpose. The furnaces 2 and 6 are not necessarily gas-heated but may be heated by any other suitable fuel.

Although it have described the material which I prefer to employ in purifying chamber 5 as consisting of charcoal and copper, it is apparent that other materials capable of exerting a purifying action on the gas used may be utilized in place thereof or I may, in some cases, dispense with such materials and cause purification to take place in an empty chamber or a chamber filled with inert material. In such case, it is generally necessary to heat the gas to a somewhat higher temperature'than if purifying material is used. These and other changes may be made in my inventionwithout departing from the scope and spirit thereof.

I claim as my invention:

' 1. A method of annealing metals which comprises placing metal to be annealed in a furnace chamber, heating the same, deoxidizing a gas and passing the same through said chamber.

2. A method of annealing metals which comprises placing metal to be annealed in a furnace chamber, heatingv the same, purifying a hydrocarbon gas and passing the same through said chamber.

3. A method of annealing metals which comprises placing metal to be annealed in a furnace chamber, heating the same, purifying natural gas and passing the same through said chamber.

4. A method of annealing metals which comprises placing metal to be annealed in a furnace chamber, heating the same, purifying a combustible gas by passing the same over suitable material for removing therefrom impurities capable of injuring the metal to be annealed and passing said gas through said chamber.

5. A method of annealing metals which comprises placing metal to be annealed in a furnace chamber, heating the same, purifying a combustible gas by passing the same over suitable material for removing oxygen, hydrogen and sulphur which are capable of injuring the metal to be annealed and passing said gas through said chamber.

6. A method of annealing metal which comfprises placing metal to be annealed in a urnace chamber, heating the same, purifying a combustible gas by passing the same over suitable heated material for removing impurities capable of injuring the metal to be annealed and passing said gas through said chamber.

7. A method of annealing metals which comprises placing metal to be annealed in a furnace chamber, heating the same, purifying a combustible gas by passing the same over a suitable metal for removing impurities capable of injuring the metal to be annealed and passing said gas through said chamber.

8. A method of annealing metals which comprises placing metal to be annealed in a furnace chamber, heating the same, purifying a combustible gas by passing the same over carbon and a suitable metal for removing from said gas impurities capable of injuring the metalto be annealed and passing said gas through said chamber.

9. A method of annealing metals which comprises placing metal 'to be annealed in a furnace chamber, heating the same, purifying acolnbustible gas by assing the same over charcoal and copper or removing impurities capable of injuring the metal to be annealed andpassing said gas through said chamber. I

10. A method of annealing metals which comprises placing metal to be annealed in a furnace chamber, heating the same. purifying a combustible gas by passing the same over'suitable heated material for removing impurities capable of injuring the metal to be annealed, passing said gas through said chamber, removing said gas therefrom and utilizing the same for heating said purifying material. a

11. A method of annealing copper which comprises placing copper to be annealed in a furnace chamber, heating the same, purifying a combustible gas and passing the same through said chamber. v

12. An apparatus for annealing metals comprising a furnace chamber, a purifying chamber, means for passing gas through said purifying chamber, and means forpass- 4 ing the same through said furnace chamber.

13. An apparatus for annealing metals comprising a furnace chamber, a purifying chamber, means for passing gas through said purifying chamber, means for heating said chambers, and means for passing said gas through said furnace chamber.

14. An apparatus for annealing metals comprising a furnace chamber, a purifying chamber, means for passing gas through said purifying chamber, material in said chamber capable of removing from said gas impurities capable of injuring the metal to be annealed and means for passing said gas through said furnace chamber.

15. Anapparatus for annealing metals comprising a furnace chamber, a purifying chamber, means for passing gas through said purifying chamber, material in said chamber capable of removing oxygen, hydrcgen and sulphur from said gas and means for passing said gas through said furnace chamber.

In testimony whereof, I have hereunto subscribed my name this 13th day of December, 1921.

CHARLES R. STEVENS. 

